Photographic optical system

ABSTRACT

The present invention discloses a photographic optical system which includes a first lens (focal length f1), a second lens (focal length f2), a third lens (focal length f3), a fourth lens (focal length f4), a fifth lens (focal length f5), a sixth lens (focal length f6) and a seventh lens (focal length f7). The photographic optical system disclosed in the present invention by optimizing rationally face shape, distributing refractive power, selecting optical material, is designed as a big relative stop photographic optical system, and can provide the imaging performance in low illumination environment.

FIELD OF THE INVENTION

The present invention discloses a photographic optical system,specifically, a photography optical system of portable electronicdevices.

DESCRIPTION OF RELATED ART

In recent years, with the vigorous development of mini photographiclens, the demand of mini picturing module is rising. The general camerasensor is either photosensitive coupling component or complementarymetal oxide conductive component. With the progress of semiconductormanufacturing technology, the sensor pixel size is smaller. Combinedwith current development trend of electronic product of better function,light, thin, short and small, as a result, the mini camera with goodimaging quality becomes the mainstream of current market.

In the camera sensor lens, the resolution of image gradually increases,pixel size decreases, the lens shall have high resolution and excellentoptical performance, for example, wide angle of lens, imaging in highdynamic range, reducing tolerance sensitivity of the lens, etc. Theexisting camera lens composed of seven pieces of lens, restricted by thestructure, is unable to correct further senior aberration, for examplespherical aberration, so that the imaging performance is limited.

Therefore, it is necessary to provide a kind of new technology solutionto overcome above disadvantage.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiment can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the present disclosure. Moreover,in the drawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is an exemplary structural diagram of a photographic opticalsystem of the present disclosure.

FIG. 2 is an MTF curve diagram of the photographic optical system shownin FIG. 1.

FIG. 3 is a field curvature curve diagram of the photographic opticalsystem in FIG. 1.

FIG. 4 is a distortion curve diagram of the photographic optical systemin FIG. 1.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The present invention will hereinafter be described in detail withreference to an exemplary embodiment. To make the technical problems tobe solved, technical solutions and beneficial effects of presentdisclosure more apparent, the present disclosure is described in furtherdetail together with the figures and the embodiment. It should beunderstood the specific embodiment described hereby is only to explainthis disclosure, not intended to limit this disclosure.

FIG. 1 is an exemplary structural diagram of a photographic opticalsystem of the present disclosure. The photographic optical system 1comprises seven lenses installed coaxially and lined up from the objectside to the image side in turn as follows: a first lens 110, a secondlens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixthlens 160 and a seventh lens 170. In this embodiment, 7 lenses above areplastic lenses.

The first lens 110 has a negative refractive power. Its object sidesurface 112 is convex and its image side surface 114 is concave. It ismade of plastic. The object side surface 112 and the image side surface114 of the first lens 110 can be spherical or aspherical.

The object side surface 122 of the second lens 120 is convex and itsimage side surface 124 is concave. It is made of plastic. The objectside surface 122 and the image side surface 124 of the second lens 120are even aspherical.

The object side surface 132 of the third lens 130 is convex and itsimage side surface 134 is convex. It is made of plastic. The object sidesurface 132 and the image side surface 134 of the third lens 130 areeven aspherical. The image side surface of the third lens has two pointsof inflection and two stagnation points.

The object side surface 142 of the fourth lens 140 is convex and theimage side surface 144 of the fourth lens 140 is concave. It is made ofplastic. The object side surface 142 and the image side surface 144 ofthe fourth lens 140 are even aspherical. The object side surface of thefourth lens has one point of inflection and one stagnation point.

The object side surface 152 of the fifth lens 150 is concave and theimage side surface 154 is convex. It is made of plastic material. Theobject side surface 152 and the image side surface 154 of the fifth lens150 are even aspherical. The image side surface of the fifth lens hasone point of inflection.

The object side surface 162 of the sixth lens 160 is concave and theimage side surface 164 is convex. It is made of plastic material. Theobject side surface 162 and the image side surface 164 of the sixth lens160 are even aspherical. The image side surface of the sixth lens hastwo points of inflection.

The object side surface 172 of the seventh lens 170 is concave and theimage side surface 174 is transferred from concave to convex fromoptical axis to circumference. It is made of plastic. The object sidesurface 172 and the image side surface 174 of the seventh lens 170 areeven aspherical. The object side surface 172 of the seventh lens 170 hasone point of inflection and one stagnation point. The image side surface174 of the seventh lens 170 has two points of inflection and onestagnation point.

In which, the object side surface is convex, referring to that theobject side surface toward the object surface is in convex shape. Theobject side surface is concave, referring to that the object sidesurface toward the object surface is in concave shape. The image sidesurface is convex, referring to that the image side surface toward theimage surface is in convex shape. The image side surface is concave,referring to that the image side surface toward the image surface is inconcave shape.

The combination refractive power of the first lens 110 and the secondlens 120 is approximate zero refractive power, can correct rationallythe spherical aberration, not introduce chromatic aberration and fieldcurvature. The fourth lens 140 and the fifth lens 150 are made ofoptical material with high refractive index and low abbe number, canreduce effectively chromatic aberration of the system. The seventh lens170 is a negative refractive power lens, can reduce effectively thefield curvature of the system. By optimizing rationally the surfaceshape of the seven lens, distributing refractive power, selectingoptical material, the photographic optical system 1 has good imagingperformance under low illumination.

The photographic optical system 1 also includes an aperture 100 and aglass plate 180. The aperture 100 is located between the second lens 120and the third lens 130, can control the amount of light and the depth offield. The glass plate 180 is located at the side of the image sidesurface 174 of the seventh lens 170. The glass plate 180 can be a filterto filter light. Its type can be selected according to actualrequirement. The image side surface 190 is the imaging side of theobject, located at the side of the glass plate 180 far from the seventhlens 170.

In the photographic optical system 1 disclosed in the present invention,in order to realize the design requirement of the photographic opticalsystem 1 on miniaturization, high sensitivity, high optical performanceand wide view angle, the first lens 110, the second lens 120, the thirdlens 130, the fourth lens 140, the fifth lens 150, the sixth lens 160and the seventh lens 170 of the photographic optical system 100 shallmeet following conditions:

1. Focal Length:

Under the overall structure of the photographic optical system 1, thefocal length of the first lens 110, the second lens 120, the third lens130, the fourth lens 140, the fifth lens 150, the sixth lens 160 and theseventh lens 170 of the photographic optical system 1 shall meet thefollowing conditions:

−5 mm<f1<−1 mm; 2 mm<f2<6 mm; 2 mm<f3<5 mm; −10 mm<f4<−2 mm;

−30 mm<f5<−10 mm; 1 mm<f6<5 mm; −5 mm<f7<−2 mm;

−1.5<f1/f<−0.5; 1.0<f2/f<2.5; 0.5<f3/f<1.5; −2.5<f4/f<−0.5;

−10<f5/f<−2; 0.2<f6/f<1.2; −2.5<f7/f<−0.4; where

f1: the focal length of the first lens,f2: the focal length of the second lens,f3: the focal length of the third lens,f4: the focal length of the fourth lens,f5: the focal length of the fifth lens,f6: the focal length of the sixth lens.f7: the focal length of the seven lens, f: the focal length of wholephotography optical system.

2. Refractive Power

Under the overall structure of the photographic optical system 1, therefractive power of the first lens 110, the second lens 120, the thirdlens 130, the fourth lens 140, the fifth lens 150, the sixth lens 160and the seventh lens 170 of the photographic optical system 1 shall meetthe conditions:

1.50<n1<1.55; 1.50<n2<1.55; 1.50<n3<1.55; 1.60<n4<1.70;

1.60<n5<1.70; 1.50<n6<1.55; 1.50<n7<1.55; where,

n1: the refractive power of the first lens,n2: the refractive power of the second lens,n3: the refractive power of the third lens,n4: the refractive power of the fourth lens,n5: the refractive power of the fifth lens,n6: the refractive power of the fifth lens,n7: the refractive power of the seven lens.

3. Abbe Number

Under the overall structure of the photographic optical system 1, Abbenumber of the first lens 110, the second lens 120, the third lens 130,the fourth lens 140, the fifth lens 150, the sixth lens 160 and theseventh lens 170 of the photographic optical system 1 shall meet theconditions:

40<v1<60; 40<v2<60; 40<v3<60; 15<v4<30; 15<v5<30;

40<v6<60; 40<v7<60; where,

v1: abbe number of the first lens,v2: abbe number of the second lens,v3: abbe number of the second lens,v4: abbe number of the fourth lens,v5: abbe number of the fifth lens,v6: abbe number of the sixth lens,v7: abbe number of the seven lens.

If the focal length, refractive power and Abbe number of the first lens110, the second lens 120, the third lens 130, the fourth lens 140, thefifth lens 150, the sixth lens 160 and the seventh lens 170 satisfy theconditions stated above, the chromatic aberration and telocentriccharacteristics of the photographic optical system 1 may be degraded,and will increase the sensitivity of the photographic optical system,difficult to realize the miniaturization and wide view angle of thephotographic optical system, and is not conducive to reduce cost of thephotographic optical system 1.

In this embodiment, the focal length, the refractive power and Abbenumber of the first lens 110, the second lens 120, the third lens 130,the fourth lens 140, the fifth lens 150, the sixth lens 160, the seventhlens 170 and the glass plate 180 of the photographic optical system 1are respectively shown in following table:

TABLE 1 Refractive Type Focal length (mm) power Abbe number Photographic3.5 — — optical system The first lens −4.591 1.5441 56.1 The second lens4.438 1.5441 56.1 The third lens 2.517 1.5441 56.1 The fourth lens−4.671 1.651 21.5 The fifth lens −20.223 1.651 21.5 The sixth lens 2.3211.5441 56.1 The seven lens −2.105 1.5441 56.1 Glass plate ∞ 1.516864.16734

The continuity of the object side surface and the image side surface,the radius of curvature, SAG and semi-diameter SD of the first lens 110(P1), the second lens 120 (P2), the third lens 130 (P3), the fourth lens140 (P4), the fifth lens 150 (P5), the sixth lens 160 (P6) and theseventh lens 170 (P7) of the photographic optical system 1 are shown intable 2:

TABLE 2 Radius of Semi-diameter Lens Continuity curvature R SAG SD P1Aspherical R11 94.687 SAG11 0.012 3.023 Aspherical R12 2.4396 SAG120.343 2.494 P2 Even R21 2.0113 SAG21 0.392 2.348 aspherical Even R2210.8108 SAG22 0.064 2.172 aspherical P3 Even R31 1.4637 SAG31 0.3161.819 aspherical Even R32 −18.9556 SAG32 −0.027 1.842 aspherical P4 EvenR41 55.361 SAG41 0.022 1.812 aspherical Even R42 2.9002 SAG42 0.1831.755 aspherical P5 Even R51 −9.3555 SAG51 −0.211 1.756 aspherical EvenR52 −32.0195 SAG52 −0.182 2.079 aspherical P6 Even R61 −5.1511 SAG61−0.200 2.782 aspherical Even R62 −1.063 SAG62 −0.595 3.335 aspherical P7Even R71 −15.1868 SAG71 −0.342 4.539 aspherical Even R72 1.256 SAG72−0.331 4.958 asphericalwhere,R11: The curvature radius of the object side surface of the first lensP1;R12: The curvature radius of the image side surface of the first lensP1;R21: The curvature radius of the object side surface of the second lensP2;R22: The curvature radius of the image side surface of the second lensP2;R31: The curvature radius of the object side surface of the third lensP3;R32: The curvature radius of the image side surface of the third lensP3;R41: The curvature radius of the object side surface of the fourth lensP4;R42: The curvature radius of the image side surface of the fourth lensP4;R51: The curvature radius of the object side surface of the fifth lensP5;R52: The curvature radius of the image side surface of the fifth lensP5;R61: The curvature radius of the object side surface of the sixth lensP6;R62: The curvature radius of the image side surface of the sixth lensP6;R71: The curvature radius of the object side surface of the seven lensP7;R72: The curvature radius of the image side surface of the seven lensP7;SAG11: the distance from the surface projection point of the first lenson the optical axis to the lens center of the object side surface;SAG12: the distance from the surface projection point of the first lenson the optical axis to the lens center of the image side surface;SAG21: the distance from the surface projection point of the second lenson the optical axis to the lens center of the object side surface;SAG22: the distance from the surface projection point of the second lenson the optical axis to the lens center of the image side surface;SAG31: the distance from the surface projection point of the third lenson the optical axis to the lens center of the object side surface;SAG32: the distance from the surface projection point of the third lenson the optical axis to the lens center of the image side surface;SAG41: the distance from the surface projection point of the fourth lenson the optical axis to the lens center of the object side surface;SAG42: the distance from the surface projection point of the fourth lenson the optical axis to the lens center of the image side surface;SAG51: the distance from the surface projection point of the fifth lenson the optical axis to the lens center of the object side surface;SAG52: the distance from the surface projection point of the fifth lenson the optical axis to the lens center of the image side surface;SAG61: the distance from the surface projection point of the sixth lenson the optical axis to the lens center of the object side surface;SAG62: the distance from the surface projection point of the sixth lenson the optical axis to the lens center of the image side surface;SAG71: the distance from the surface projection point of the seven lenson the optical axis to the lens center of the object side surface;SAG72: the distance from the surface projection point of the seven lenson the optical axis to the lens center of the image side surface.

The thickness of the first lens 110 (P1), the second lens 120 (P2), theaperture 100 (ST), the third lens 130 (P3), the fourth lens 140 (P4),the fifth lens 150 (P5), the sixth lens 160 (P6), the seventh lens 170(P7) and the glass plate 180 (Tg) of the photographic optical system 1is shown in table 3:

TABLE 3 Thickness (mm) T1 0.250 T12 0.140 T2 0.500 ST 0.345 T23 −0.245T3 0.646 T34 0.050 T4 0.250 T45 0.394 T5 0.250 T56 0.313 T6 0.663 T670.306 T7 0.450 Tg 0.221

Where,

T1: The thickness of the first lens;T12: The axial distance from the image side surface of the first lensand the object side surface of the second lens;T2: The thickness of the second lens;ST: The axial distance from the image side surface of the second lens tothe aperture;T23: The axial distance from the aperture to the object side surface ofthe third lens;T3: The thickness of the third lens;T34: The axial distance from the image side surface of the third lensand the object side surface of the fourth lens;T4: The thickness of the fourth lens;T45: The axial distance from the image side surface of the fourth lensto the fifth lens;T5: The thickness of the fifth lens;T56: The axial distance from the fifth lens to the sixth lens;T6: The thickness of the sixth lens;T67: The axial distance from the sixth lens to the seventh lens;T7: The thickness of the seventh lens.

TABLE 4 Relation table between main light angle CRA and the image heightof the photographic optical system Biggest image height percentage Imageheight (mm) CRA (degree) 0.1H 0.294 6.6 0.2H 0.588 13.0 0.3H 0.882 19.00.4H 1.176 24.3 0.5H 1.470 28.5 0.6H 1.764 31.0 0.7H 2.058 31.3 0.8H2.352 32.1 0.9H 2.646 33.2 1.0H 2.94 32.3 max — 33.2

In this embodiment, DFOV=78.93 degrees, HFOV=66.88 degrees, VFOV=52.59degrees, in which: FOV is defined as the biggest view angle range of thephotographic optical system, HFOV is defined as horizontal view angle,DFOV is defined as diagonal view angle, VFOV is defined as vertical viewangle.

Please refer also to FIGS. 2-4, the photographic optical system 1disclosed in the present invention has high optical performance.

In addition, in the photographic optical system 1 disclosed in thepresent invention, the photographic optical system 1 is designed on thebasis of the optical system with large relative aperture. Total opticallength is less than 5.2 mm, view angle is between 78 degree to 80degree.

The photographic optical system 1 disclosed in the present invention hasfollowing beneficial effects:

In present invention, through optimizing surface type, distributingfocal power, selecting optical material, a big relative aperturephotographic optical system is designed, which can provide good imagingperformance in low illumination environment. The image is clear. Thecombination focal power of the first lens 110 and the second lens 120 isapproximate zero focal power lens, can correct rationally the sphericalaberration, not introduce chromatic aberration and field curvature. Thefourth lens 140 and the fifth lens 150 are made of material with highrefractive index and low abbe number, can reduce effectively chromaticaberration of the system. The seventh lens 170 is negative focal powerlens which can reduce effectively the field curvature of the system.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present exemplary embodiment havebeen set forth in the foregoing description, together with details ofthe structures and functions of the embodiment, the disclosure isillustrative only, and changes may be made in detail, especially inmatters of shape, size, and arrangement of parts within the principlesof the invention to the full extent indicated by the broad generalmeaning of the terms where the appended claims are expressed.

What is claimed is:
 1. A photographic optical system comprising, in anorder from an object side to an image side: a first lens having anegative refractive power and an object side surface thereof beingconvex; a second lens, a third lens, a fourth lens, a fifth lens, asixth lens; and a seventh lens having negative refractive power; whereinthe photographic optical system further meets the following conditions(1)˜(7):−1.5<f1/f<−0.5  (1)1.0<f2/f<2.5  (2)0.5<f3/f<1.5  (3)−2.5<f4/f<−0.5  (4)−10<f5/f<−2  (5)0.2<f6/f<1.2  (6)−2.5<f7/f<−0.4  (7) where, f1: The focal length of the first lens; f2:The focal length of the second lens f3: The focal length of the thirdlens f4: The focal length of the fourth lens f5: The focal length of thefifth lens f6: The focal length of the sixth lens f7: The focal lengthof the seven lens f: The focal length of whole photography opticalsystem.
 2. The photographic optical system as described in claim 1further satisfying the following conditions (8)˜(28):−5 mm<f1<−1 mm  (8)1.50<n1<1.55  (9)40<v1<60  (10)2 mm<f2<6 mm  (11)1.50<n2<1.55  (12)40<v2<60  (13)2 mm<f3<5 mm  (14)1.50<n3<1.55  (15)40<v3<60  (16)−10 mm<f4<−2 mm  (17)1.60<n4<1.70  (18)15<v4<30  (19)−30 mm<f5<−10 mm  (20)1.60<n5<1.70  (21)15<v5<30  (22)1 mm<f6<5 mm  (23)1.50<n6<1.55  (24)40<v6<60  (25)−5 mm<f7<−2 mm  (26)1.50<n7<1.55  (27)40<v7<60  (28) where, f1: The focal length of the first lens; n1: Therefractive power of the first lens; v1: Abbe number of the first lens;f2: The focal length of the second lens; n2: The refractive power of thesecond lens; v2: Abbe number of the second lens; f3: The focal length ofthe third lens; n3: The refractive power of the third lens; v3: Abbenumber of the third lens; f4: The focal length of the fourth lens; n4:The refractive power of the fourth lens; v4: Abbe number of the fourthlens; f5: The focal length of the fifth lens; n5: The refractive powerof the fifth lens; v5: Abbe number of the fifth lens; f6: The focallength of the sixth lens; n6: The refractive power of the sixth lens;v6: Abbe number of the sixth lens; f7: The focal length of the sevenlens; n7: The refractive power of the seven lens; v7: Abbe number of theseven lens.
 3. The photography optical system as described in claim 2,wherein the first lens and the second lens are almost zero focal powerlenses for correcting rationally the spherical aberration, and thephotography optical system further meets the following condition:f1-2>60 mm or f1-2<−50 mm  (29) where, f1-2: The combination focallength of the first lens and the second lens.
 4. The photographicoptical system as described in claim 1, wherein a ratio between thefocal length and the system total optical length of the photographicoptical system meets the following condition:f/TTL>0.65  (30) where, TTL: The distance from the object side surfaceto imaging surface of the first lens.
 5. The photography optical systemas described in claim 1, wherein the fourth lens and the fifth lens aremade of material with high refractive index and low abbe number, whichcan correct rationally the chromatic aberration of the system, and thefourth lens meets the conditions:1.60<n4<1.70; 15<v4<30; and the fifth lens meets the conditions:1.60<n5<1.70; 15<v5<30.
 6. The photographic optical system as describedin claim 1, wherein the seventh lens is a negative lens and meets thecondition:−5 mm<f7<−2 mm
 7. 7. The photography optical system as described inclaim 2, wherein the photographic optical system also meets thefollowing conditions:TTL<5.4 mm;78°<FOV<88°; where, TTL: The distance from the object side surface tothe imaging surface of the first lens; FOV: The biggest view angle rangeof the photographical optical system.
 8. The photography optical systemas described in claim 5, wherein the object side surface of the fourthlens, the image side surface of the fifth lens and the object sidesurface of the seventh lens have one inflexion point respectively; theimage side surface of the third lens, the image side surface of thesixth lens and the image side surface of the seventh lens have twoinflexion points respectively.
 9. The photography optical system asdescribed in claim 6, wherein the image side surface of the third lenshas two stagnation points; the object side surface of the fourth lens,the object side surface and the image side surface of the seventh lenshave one stagnation point respectively.
 10. The photography opticalsystem as described in claim 1, wherein the first lens, the second lens,the third lens, the fourth lens, the fifth lens, the sixth lens and theseventh lens are plastic lenses.